I experience an odd divide regarding kiai. Henry Smith Shihan advocates a silent kiai. Breath is meant to accompany every movement as described in post #2 above but my weapons sensei, Nizam Taleb (go dan) emphasized an articulated sound similar to karate. (We even practiced separating kiai from movement to unsettle the rhythm of uke.) I cannot say if I am comfortable with this because I have practiced this way for so long or if the articulation truly is more natural with weapons. My suggestion is experiment. Truth is revealed in action.